FIG. 1 is a block diagram describing a node signal receiving device in a RF system in prior art. As shown in FIG. 1, the node signal receiving device in a RF system comprises a digital demodulating block for performing ASK demodulation through SQR(Square Root) signal conversion that squares negative data of I channel node signal and Q channel node signal and transforms squared data to negative data and a decoding block for detecting edge position information by using the integration of demodulated signal and decoding said demodulated signal by using detected edge position information. Meanwhile, the digital demodulating block comprises a phase shifter for shifting phase of the node signal whose signal level is lower than the other between the node signals of I channel and Q channel outputted from ADC(Analog to Digital Converter), a signal converter for performing SQR signal conversion onto phase-shifted node signal and the node signal which has higher signal level, and a adder for adding converted node signal of I channel and converted node signal of Q channel.
Furthermore, the decoding block comprises an edge information detector for detecting edge position information of a demodulated signal, a correlator for performing signal correlation onto the demodulated signal by using detected edge position information and a bit data decider for deciding bit data by using signal correlation result.